Cast puppet-valve



' Fa HILTY.

CAST PUPPETVALVE- APPLICATION FILED JULY 3,1919.

Patented July 27, 1920.

5/ FEderla/t HZZZQ UNITED STATES PATENT OFFICE.

FREDERICK HILTY, 0F WAUKEG-AN, ILLINOIS, ASSIGNOR TO LAURENCE R. WILDER,

OFv COOK COUNTY, ILLINOIS.

oasr PUPPET-VALVE.

Specification of Letters Patent.

Patented July 2'7, 1920.

Original a lication filed March 28, 1919, Serial No. 285,866. Divided and this application filed July 3,

1919. Serial No. 308,681.

'of Illinois, have invented a certain new and useful Improvement in Cast Puppet-Valves,

of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, formin a part of this specification.

My invention relates to puppet valves such as are commonly used in connection with internal combustion engines and the object of my invention is to provide a pup pet valve of this class which, while cast entirely from molten metal, is of greatest density in the head, which, in valves of this class is, of course, the part which on an engine is subjected to the most violent usage and which -moreover, is the part of the valve which in order togive satisfactory service should be capable of withstanding a maximum amount of pounding under high temperatures without losing its proper shape and proper registry with its cooperating seat. a

Cast puppet valves heretofore have been subjected to serious objection, due to the inability of the cast metal wh1ch was of the same comparatively low density at all points, including the valve head, to stand up under the mechanical abuse to which puppet valves are subjected in the ordinary operation of an internal combustion engine. Because of this fact, it has been proposed to provide high grade engines with pup et valves of high speed steel throughout which, however, are necessarily very expensive because of the high cost of the high speed steel and the difiiculty of its manufacture. Moreover, valves of high speed steel throughout are furthermore objectionable because high speed steel is not a suitable material for a valve stem on account of the tendency of the stem to expand and jam in its valve stem guide. Valves have also been provided which comprise high speed steel heads having stems of" carbon steel or other steel of lower grade fused thereto. These have, perha s, been the most satisfactory valves hereto ore provided, but, of course, are somewhat expensive due to the cost of material and the hi hly skilled labor required for their manufacture.

rotatable housing or case.

My invention contemplates the provision of a puppet valve which is cast entire from molten metal by a single operation and therefore, may be cheaply manufactured. The valve furthermore is characterized, not only by the fact that it is of greater density throughout than are puppet valves cast by the processes heretofore employed, but is also characterized by the fact that the metal constituting the head and the junction of head and stem is of greater density than the metal constituting the stem. Thus, I have provided a cast metal puppet valve, the metal constituting which is of different densities with the metal of greatest density in the head.

In casting the puppet valve of my invention, any suitable means may be employed, but I prefer to use the apparatus shown and described in Patent No. 1,329,179 granted to me January 27, 1920 and of wl1ich this application is a division. The method disclosed in my patent comprises a plurality of molds of the conformation of the desired valve arranged radially within a suitable An-ope'ning is provided within the housing which is arranged to receive the molten metal to be cast into puppet valves and as the housing is rotated centrifugal force carries the metal through sprue openings, into the molds. Each of the several valve molds, being arranged radially, has the head and neck portions farthest away from the central opening in the housing and as the molten metal is supplied, it flows through the mold cavities forming first the head and neck portions and then the valve stem. The metal is supplied with the housing in motion. The centrifugal stress being the greatest at the head and adjacent portions of the valve mold cavities, valves having the desired varying densities are formed.

I have found that upon cooling there is a tendency for the metal constituting the valve stem to pull away from the metal constituting the valve head upon shrinkage due to cooling, this probably due to the fact that the cross-section of the valve head, being greater than that of the adjacent portion of the stem, the molten metal constituting the stem cools more rapidly than that constituting the head.

I have found that the use of a metallic pin or nail extending-through the mold molten metal where the head joins thestem and thus overcomes any tendency for separation at this point.

Referring to the drawings,

Figure 1 is a perspective view of the valve of my invention after the same'is cast and before any machining operations are effected, and

Fig. 2 is an axial sectional view of the valve, the cross-hatching being shaded somewhat to illustrate the varying densities.

In the drawings, 7 illustrates a valve having a stem 8 and a head 9. Before the valve is cast in accordance with my invention, a metallic pin or nail 10 is extended through the mold into the portion of the mold cavity Whereinthe head and upper portion of the stem are formed so that when the molten metal is carried into the mold, the metal at the junction of head and stem is at once chilled sufiiciently to prevent separation of the metal at the joint. The purpose and advantages of the element 10 are more fully set forth in my patent aforesaid.

In order to render the valve capable of use on an engine, the metal member or nail 10 is out 01f flush with the upper surface of the valve head, the valve stem is cut to the proper length, and the casting has such finishing operations performed thereon as may be deemed necessary or desirable.

Microphotographs of sections of my improved cast puppet valve when compared with similar microphotographs of puppet valves made by the ordinary methods, clearly reveal that the metal constituting any given part of my valve is of greater density than the metal constituting any part of the ordinary cast valves heretofore mentioned. Moreover, a comparison of microphotographs of-the different parts of my improved valve demonstrate that the metal is of different densities with the metal of greatest density in the head and junction of head and stem. The obvious advantage of this feature of my valve is, of course, its ability to withstand the abuse to which it is subjected on an engine.

This application is divisional of my copending application, Serial N 0. 285,866, filed March 28th, 1919.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent of the United States is 1. An integrally cast metal puppet valve inwhich the metal constituting the head and upper portion of the stem is of greater density than the metal at the lower end of the stem.

2. An integrally cast metal puppet valve for internal combustion engines which is of varying density, being most dense in the head and least dense at the lower end of the stem.

3. An integrally cast metal puppet valve which is of greater density in the head and at the junction of head and stem than at the lower end of the stem.

In witness whereof, I hereunto subscribe my name this 23 da of June 1919.

F DERIK HILTY. Witnesses: ELLA M. NEEDHAM, MILDRED V. BUDDE. 

